Because of a general difference in the electrical potentials between a metallic product and a roller-conveyor roll, electrical currents and spark formation can result in surface defects in the manufactured material.
It is known (DE 24 26 135 C2) to provide a roller-conveyor roll for the transport of rolled products such as rolling mill products which can resist impact with the rolled product. It has not been noted therein that such roller-conveyor rolls also contribute to electrical currents and spark formation which can degrade the rolled product.